Linux Networking: Setting Up A Vpn With Openvpn

Linux Networking: Setting Up a VPN with OpenVPN

Virtual Private Networks (VPNs) are essential for secure and private online communication. They allow you to create an encrypted tunnel between your device and a remote server, protecting your data from eavesdropping and censorship. OpenVPN is a widely used open-source VPN protocol known for its reliability and security.

Installing OpenVPN

Before setting up OpenVPN, you need to install it on your Linux system. Depending on your distribution, you can use the following commands:

• Debian/Ubuntu: apt-get install openvpn
• Arch Linux: pacman -S openvpn

Generating Certificates

To establish a secure VPN connection, you need to generate public/private key pairs and certificates for both the server and client. Use the following commands on the server and client to generate these credentials:

• Server:

openssl genrsa 4096 > server.key
openssl req -new -x509 -key server.key -sha256 -days 3650 -out server.crt

• Client:

openssl genrsa 4096 > client.key
openssl req -new -key client.key -sha256 -out client.csr

Sign the client certificate using the server’s certificate:

openssl x509 -req -in client.csr -CA server.crt -CAkey server.key -CAcreateserial -out client.crt

Configuring OpenVPN Server

Create a server configuration file (/etc/openvpn/server.conf) with the following contents:

port 1194
proto udp
dev tun
ca server.crt
cert server.crt
key server.key
dh dh.pem
server 10.8.0.0 255.255.255.0
push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 8.8.8.8"
keepalive 10 120
cipher AES-256-CBC
user nobody
group nogroup
persist-key
persist-tun
status /var/log/openvpn-status.log
verb 3

• Change 10.8.0.0 to the subnet you want to use for the VPN.
• Adjust cipher to your desired encryption level.

Configuring OpenVPN Client

Create a client configuration file (/etc/openvpn/client.conf) on the client system:

remote <server_IP_or_FQDN> 1194
proto udp
dev tun
ca server.crt
cert client.crt
key client.key
cipher AES-256-CBC
user nobody
group nogroup
persist-key
persist-tun
status /var/log/openvpn-status.log
verb 3

• Replace <server_IP_or_FQDN> with the server’s address.

Starting and Connecting

To start the OpenVPN server and listener, run:

 systemctl enable --now openvpn-server@server
 systemctl start openvpn-server@server

On the client, connect to the VPN using:

 openvpn --config client.conf

Troubleshooting

If you encounter any issues, check the following:

• Verify that your firewall is allowing traffic on port 1194.
• Ensure that your certificates and configuration files are valid.
• Check the server and client log files for any errors.

By following these steps, you can establish a secure and private VPN connection using OpenVPN on your Linux system.